| Popis: |
The Neopretorozoic carbonate reservoirs of the South Oman Salt Basin are considered the oldest producing reservoirs in the world. These carbonate stringer units, fully encased in salt, form a unique hydrocarbon system with proven economic viability. The greatest challenge in exploring and producing hydrocarbons in these stringer reservoirs, lies in the ability to confidently visualize them and predict their properties. An additional challenge is mapping the top of the salt. This impacts the time-todepth conversion of the reservoir interval and hence the geometry of the structure, which has direct bearing on the calculated hydrocarbons-in-place. Over the years, the top salt pick was solely made based on the seismic data. Gravity data, which in general has a good lateral resolution and poor vertical resolution, was mostly used to validate this pick. This worked well in areas where the top salt interface forms a strong reflector. This occurs where the salt is overlain by a thick carbonate unit, or in places where a significant impedance contrast exists with the overlying conglomerates or sand of the Haima pods. Integration of well and seismic data, using seismic modelling and seismic-to-well ties, showed that mapping the top salt depended on the ability to predict the lateral extent of the carbonate layer overlying the salt. By combining the understanding of the seismic response. together with a basic geological model of the extent of the carbonate, facilitated capturing the uncertainties in the top salt map. |
